Re: How do I add a column to an existing table.

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От John Draper
Тема Re: How do I add a column to an existing table.
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Msg-id v03110701b5eae6d9b7f5@[24.12.41.181]
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Ответ на How do I add a column to an existing table.  (John Draper <crunch@webcrunchers.com>)
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>Please don't take offense but there's a few points you need to
>realize:
>
>1) I'm just a volunteer and don't have time to research the
>   exact sequence of commands for you, (it looks like you didn't
>   even try to read the docs between getting my response and
>   emailing me back)

I did read the docs and I don't understand them,  and I cannot possibly
guess what commend to make...  I can ONLY learn by example.

>2) you need to read the docs.

I did - over and over and over again... linearly,   and reference it
constantly - their examples do NOT cover every case.

>3) in the future please post your replies back to the main list
>   so that if I happen to go someplace else or miss your mail someone
>   else may be able to pick it up.

Ok,    I was just trying to cut down on bandwidth,  thats all.
>
>read on, I'll give you more info on how to achive what you want.

>Of course you care, pg_dump can be told to dump to an output file.
>
>And don't loose it!  in fact it's probably a good idea to view it
>and make sure it contains all your data then making sure you back
>it up to another machine before dropping the table.
>
>> >You then should be able to run the insert statements and get a unique
>> >key for each row.
>>
>> Again,   an exact set of commands to do this,   would be most helpful.
>> I'm having problems understanding the Docs.   SQL is really new to me.
>
>you should be able to just run 'psql < dumpfile' and psql will run
>all the commmands in the file to do the insertion.

Do I run this from the system shell promot like "bash" or do I run it from
within the "psql" program?   And where in the docs do they explain this?
>
>> >Another way would be to just add the column, then run a query to set
>> >the key == 'oid', you'd then have to create a sequence, and set it's
>> >value to 'max(key)' then make the key column's default to
>> >'nextval(''your sequewnce name'')' unfortunatly you can't make 'key'
>> >the first column.

I'm just guessing here,   but would it look like this?

CREATE SEQUENCE users_seq;    <--- to create the sequence

CREATE TABLE temp_users (key int DEFAULT nextval('users_seq'),  first_name
char(15),  last_name char(15)    <etc>

Is THAT how I would do it?

John



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